It’s a natural treat loved by people around the world. For a lot of moviegoers, a night out at the cinema wouldn’t be the same without it. Many adults and kids also delight in making it at home to snack on. After all, it’s hard not to love a food that explodes. But why exactly does popcorn blow up and turn into something delicious?
In fact, the science behind popcorn is fairly simple. With popcorn, there are three main factors at work. Firstly, the kernel, or seed, of popcorn contains a small amount of water, along with a large amount of starch. Secondly, the outer shell of the kernel, which is called the hull, is strong and traps water inside it. Thirdly, when heated enough, the water expands into steam. This steam makes the starch softer. It also produces pressure inside the kernel. Since the steam cannot escape from the hull, it eventually explodes. When that happens, the kernel basically turns inside out.
Does all corn act this way? No, the corn that people commonly eat is a variety known as sweet corn. No matter how long someone leaves sweet corn on a barbecue or in an oven, it won’t burst into little puffs. The popcorn people eat comes from a variety of corn that is itself called popcorn.
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Another interesting fact about popcorn is related to the reason that it makes a bang when it pops. It was once thought that the sound came from the kernel breaking. However, scientists discovered it is actually due to the sudden release of water vapor from the kernel. In other words, this swift change in air pressure produces the popping sound.
它是一種受到世界各地人們喜愛的天然美味食物。對很多常去看電影的人來說，如果沒有它，在電影院的夜晚就會有所不同。許多大人和小孩也喜歡在家裡做這道點心吃。畢竟，很難不愛上會爆開的食物。但爆米花究竟為什麼會爆，並變成美味的東西呢？
事實上，爆米花背後的科學原理相當簡單。這當中有三個主要因素影響著。首先，爆米花的玉米粒（或種子）含有少量的水分和大量的澱粉。其次，玉米粒的外殼（hull）很結實，會把水分存在裡頭。第三，當加熱至夠熱時，水會膨脹成蒸氣。這些蒸氣使澱粉變得較軟。它還會在玉米粒內部產生壓力。由於蒸氣無法從外殼溢出，外殼最終就爆開了。這種情況發生時，玉米粒基本上就會外翻過來。
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所有的玉米都會這樣嗎？不，一般人們常吃的玉米是一種被稱為甜玉米的品種。無論將甜玉米放在烤肉架上或烤箱中多久，它都不會爆裂成蓬鬆的米花。人們吃的爆米花來自一種本身叫做爆米花的玉米品種。
另一個關於爆米花的有趣事實是關乎爆米花爆裂時產生砰砰聲的原因。曾有人認為，這個聲音是因為玉米粒破裂。然而，科學家發現，事實上砰砰聲是因為玉米粒中突然釋放的水蒸氣。換句話說，是這種氣壓的迅速變化產生了爆裂聲。
Words in Use
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1. delight vi. & n. 高興，欣喜
delight in. . . 喜歡（做）…，以…為樂
= take delight in. . .
Emily really delights in playing the piano.
艾蜜莉真的很喜歡彈鋼琴。
2. explode vi. 爆炸
= blow up
My can of soda exploded in the freezer.
我放在冷凍庫裡的罐裝汽水爆開來了。
3. fairly adv. 相當地；頗
John did fairly well in the speech contest and got a good score.
約翰在演講比賽中的表現相當不錯，得到很好的成績。
4. factor n. 因素
The controversial issue was complicated by many factors.
諸多因素使得這項具爭議性的問題更加複雜。
Practical Phrases
1. snack on. . . 吃…（當點心）
snack vi. 吃點心; n. 點心
Wally likes to snack on potato chips and soft drinks. 瓦利喜歡吃洋芋片和喝汽水。
2. at work 起作用，產生影響
Rock formations are a perfect example of weathering at work. 岩石的的形成是風化作用產生影響的最佳範例。
* weathering n. 風化（作用）
3. escape from. . . 逃離…
However hard it tried, the bird couldn’t escape from the cage.
這隻鳥無論多努力嘗試，都無法逃出鳥籠。
4. inside out 裡外顛倒地
Henry went out hurriedly and didn’t notice that he was wearing his coat inside out.
亨利匆忙出門，沒注意到自己將外套穿反了。
聽文章朗讀及講解: https://ivy.pse.is/455bfu
本文出自常春藤解析英語雜誌: www.ivy.com.tw
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